Learn more about combustion in Chemical World 14.1
The combustion of fuels also releases carbon to the atmosphere in the form of carbon dioxide. Increased levels of carbon dioxide in the atmosphere causes air pollution and global warming.
Green plants absorb CO2 CO2
Combustion gives off CO2
Animals respire and give off CO2
z
Fig. 22.2.3
The cycling of carbon in the atmosphere
Carbon in the news
The terms ‘carbon budget’ and ‘carbon footprint’ are often used by the media to report on the causes and effects of changing carbon levels in our atmosphere.
Research simple definitions for each of these terms and give one example of their use in a news headline.
The Nitrogen Cycle
Nitrogen is another important element for living organisms. It is an important part of many proteins and other structures in cells. Nitrogen is also important for the building of DNA.
Like carbon, nitrogen is released from the rocks of the Earth’s crust very slowly.
z Fig. 22.2.4 Carbon footprint The nitrogen cycle explains how nitrogen is recycled through the Earth.
Decomposers break down dead plant and animal matter and give off CO2
